/*
 *	Copyright (C) 2009,2011 by Jonathan Naylor, G4KLX
 *
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation; version 2 of the License.
 *
 *	This program is distributed in the hope that it will be useful,
 *	but WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *	GNU General Public License for more details.
 */

#include "CCITTChecksumReverse.h"

#include "Utils.h"

static const unsigned short ccittTab[] = {
	0x0000,0x1189,0x2312,0x329b,0x4624,0x57ad,0x6536,0x74bf,
	0x8c48,0x9dc1,0xaf5a,0xbed3,0xca6c,0xdbe5,0xe97e,0xf8f7,
	0x1081,0x0108,0x3393,0x221a,0x56a5,0x472c,0x75b7,0x643e,
	0x9cc9,0x8d40,0xbfdb,0xae52,0xdaed,0xcb64,0xf9ff,0xe876,
	0x2102,0x308b,0x0210,0x1399,0x6726,0x76af,0x4434,0x55bd,
	0xad4a,0xbcc3,0x8e58,0x9fd1,0xeb6e,0xfae7,0xc87c,0xd9f5,
	0x3183,0x200a,0x1291,0x0318,0x77a7,0x662e,0x54b5,0x453c,
	0xbdcb,0xac42,0x9ed9,0x8f50,0xfbef,0xea66,0xd8fd,0xc974,
	0x4204,0x538d,0x6116,0x709f,0x0420,0x15a9,0x2732,0x36bb,
	0xce4c,0xdfc5,0xed5e,0xfcd7,0x8868,0x99e1,0xab7a,0xbaf3,
	0x5285,0x430c,0x7197,0x601e,0x14a1,0x0528,0x37b3,0x263a,
	0xdecd,0xcf44,0xfddf,0xec56,0x98e9,0x8960,0xbbfb,0xaa72,
	0x6306,0x728f,0x4014,0x519d,0x2522,0x34ab,0x0630,0x17b9,
	0xef4e,0xfec7,0xcc5c,0xddd5,0xa96a,0xb8e3,0x8a78,0x9bf1,
	0x7387,0x620e,0x5095,0x411c,0x35a3,0x242a,0x16b1,0x0738,
	0xffcf,0xee46,0xdcdd,0xcd54,0xb9eb,0xa862,0x9af9,0x8b70,
	0x8408,0x9581,0xa71a,0xb693,0xc22c,0xd3a5,0xe13e,0xf0b7,
	0x0840,0x19c9,0x2b52,0x3adb,0x4e64,0x5fed,0x6d76,0x7cff,
	0x9489,0x8500,0xb79b,0xa612,0xd2ad,0xc324,0xf1bf,0xe036,
	0x18c1,0x0948,0x3bd3,0x2a5a,0x5ee5,0x4f6c,0x7df7,0x6c7e,
	0xa50a,0xb483,0x8618,0x9791,0xe32e,0xf2a7,0xc03c,0xd1b5,
	0x2942,0x38cb,0x0a50,0x1bd9,0x6f66,0x7eef,0x4c74,0x5dfd,
	0xb58b,0xa402,0x9699,0x8710,0xf3af,0xe226,0xd0bd,0xc134,
	0x39c3,0x284a,0x1ad1,0x0b58,0x7fe7,0x6e6e,0x5cf5,0x4d7c,
	0xc60c,0xd785,0xe51e,0xf497,0x8028,0x91a1,0xa33a,0xb2b3,
	0x4a44,0x5bcd,0x6956,0x78df,0x0c60,0x1de9,0x2f72,0x3efb,
	0xd68d,0xc704,0xf59f,0xe416,0x90a9,0x8120,0xb3bb,0xa232,
	0x5ac5,0x4b4c,0x79d7,0x685e,0x1ce1,0x0d68,0x3ff3,0x2e7a,
	0xe70e,0xf687,0xc41c,0xd595,0xa12a,0xb0a3,0x8238,0x93b1,
	0x6b46,0x7acf,0x4854,0x59dd,0x2d62,0x3ceb,0x0e70,0x1ff9,
	0xf78f,0xe606,0xd49d,0xc514,0xb1ab,0xa022,0x92b9,0x8330,
	0x7bc7,0x6a4e,0x58d5,0x495c,0x3de3,0x2c6a,0x1ef1,0x0f78};

CCCITTChecksumReverse::CCCITTChecksumReverse() :
m_crc16(0xFFFFU)
{
}

CCCITTChecksumReverse::~CCCITTChecksumReverse()
{
}

void CCCITTChecksumReverse::update(const unsigned char* data, unsigned int length)
{
	wxASSERT(data != NULL);

	for (unsigned int i = 0U; i < length; i++)
		m_crc16 = wxUint16(m_crc8[1U]) ^ ccittTab[m_crc8[0U] ^ data[i]];
}

void CCCITTChecksumReverse::update(const bool* data)
{
	wxASSERT(data != NULL);

	unsigned short byte = CUtils::bitsToByte(data);

	m_crc16 = wxUint16(m_crc8[1U]) ^ ccittTab[m_crc8[0U] ^ byte];
}

void CCCITTChecksumReverse::result(unsigned char* data)
{
	wxASSERT(data != NULL);

	m_crc16 = ~m_crc16;

	data[0U] = m_crc8[0U];
	data[1U] = m_crc8[1U];
}

void CCCITTChecksumReverse::result(bool* data)
{
	wxASSERT(data != NULL);

	m_crc16 = ~m_crc16;

	unsigned char mask = 0x80U;
	for (unsigned int i = 0U; i < 8U; i++, mask >>= 1)
		data[i + 0U] = (m_crc8[0U] & mask) ? true : false;

	mask = 0x80U;
	for (unsigned int i = 0U; i < 8U; i++, mask >>= 1)
		data[i + 8U] = (m_crc8[1U] & mask) ? true : false;
}

bool CCCITTChecksumReverse::check(const unsigned char* data)
{
	wxASSERT(data != NULL);

	unsigned char sum[2U];
	result(sum);

	return sum[0U] == data[0U] && sum[1U] == data[1U];
}

bool CCCITTChecksumReverse::check(const bool* data)
{
	wxASSERT(data != NULL);

	bool sum[16];
	result(sum);

	for (unsigned int i = 0U; i < 16U; i++) {
		if (sum[i] != data[i])
			return false;
	}

	return true;
}

void CCCITTChecksumReverse::reset()
{
	m_crc16 = 0xFFFFU;
}
